Decoder



SOURCE INVEN TOR.

ALEXANDER GREENFELD United States Patent O DECUDER Alexander Greenfield,Detroit, Mich., assignor to Bendix Aviation Corporation, Detroit, Mich.,a corporation of Delaware Application November 2, 1950, Serial No.193,735 Claims. (Cl. Z50- 27) This invention relates to an electricalsystem for determining the time intervals between successive pulses andmore particularly to a system for producing signals recurring atpredetermined intervals between successive pairs of adjacent pulses.

In the present electronic applications, a series of pulses is oftenformed to provide information on the basis of the separation betweenpulses. The pulses are transmitted to a distant station where they aredecoded, recorded and analyzed. The systems now in use for decoding thetime periods between successive pulses do not convert the periods into aform which can be easily recorded and analyzed. Furthermore, thecircuits are relatively complex and bulky.

This invention provides a system which produces signals recurring atpredetermined intervals during each period defined by adjacent pulses.The signals are in a positive form so that they can be easily counted todetermine each time period. The system requires a minimum number ofparts, including vacuum tubes, and provides a maximum amount ofstability and reliability.

An object of this invention is to provide a system for determining theperiod of time between adjacent pulses.

Another object is to provide a system of the above character forconverting the period of time between successive pulses into a positiveform which can be stored and subsequently recorded and analyzed.

A further object is to provide a system of the above character forproducing positive pips at predetermined intervals during each perioddened by adjacent pulses.

Still another object is to provide a system of the above charactergiving a maximum amount of eiiciency with a minimum number of parts.

Other objects and advantages will be apparent from a detaileddescription of the invention and from the appended drawings and claims.

In the drawings:

Figure 1 is a block diagram of a system constituting one embodiment ofthe invention; and

Figure 2 illustrates wave forms of voltages at strategic points in thesystem shown in Figure l.

In one embodiment of the invention, negative triggering signals areintroduced from a source 10 through a coupling capacitance 12 to thegrids of the left and right tubes in a bistable multivibrator 14 and tothe grids of the right tubes in bistable multivibrators 16 and 18. Eachmultivibrator has a pair of capacitances which connect the grid of onetube to the plate of the other tube in the multivibrator. Thus,capacitances 20 and 22, capacitances 24 and 26 and capacitances 28 and30 are provided in the multivibrators 14, 16 and 18, respectively.

The plate of the left tube in the multivibrator 14 is connected to thegrids of the two tubes in a biased multivibrator 32 and to the grid ofthe left tube in the multivibrator 16. The plate of the right tube inthe multivibrator 14 is connected to the control grid of a pentode in agating circuit 34.

The plate of the left tube in the multivibrator 16 is connected to thegrids of the two tubes in a biased multivibrator 36, as well as to thegrid of the left tube in the multivibrator 18. The plate of the righttube in the multivibrator 16 is connected through a coupling capacitance38 to the control grid of a pentode in a gating circuit 40, similar tothe gating circuit 34.

A connection is made between the plate of the left tube in themultivibrator 18 and the control grid of a pentode in a gating circuit42, similar to the gating circuits 34 and 40. The plate of the righttube in the multivibrator 18 is connected to the control grid of thepentode in the gating circuit 40.

The plate of the left tube in the biased multivibrator 32 is connectedto the suppressor grid of the pentode in the gating circuit 42, as wellas to the suppressor grid of the pentode in the gating circuit 4I). fromthe gating circuits 40 and 42 are taken from leads 44 and 46,respectively. In like manner, a connection is made between the plate ofthe left tube in the biased multivibrator 36 and the suppressor grid ofthe pentode in the gating circuit 34, and the output from the gatingcircuit 34 is taken from a lead 48.

The left tubes of the multivibrators 14, 16 and 18 are normallyconductive.

grid of the right tube in the multivibrator, causing the right tube toconduct. The increased voltage on the plate of the left tube in themultivibrator 14 continues until a second negative triggering signal,indicated at 52, is introduced to the grids of the two tubes` in themultivibrator. The right tube then becomes cut off, and the left tubeagain starts to conduct through the action of the capacitance 20.

Since the left tube of the multivibrator 14 it cut oi between thetriggering signals 50 and 52, a positive pulse, indicated at 54, isproduced on its plate during this period. A positive pulse, indicated at56, is also produced on the plate of the left tube in the multivibrator14 during the period between third and fourth negative triggeringsignals 58 and 60, and a complementary positive pulse, indicated at 62,is formed on the plate of the right tube during the period between thesignals 52 and 58.

The voltage on the grid of the left tube in the multivibrator 16 followsthe voltage on the plate of the left tube in the multivibrator 14 andbecomes negative upon the introduction of the triggering signal 52 tothe multivibrator 14. The left tube in the multivibrator 16 is then cutoif, and a positive pulse, illustrated at 64 in Figure 2, is produced onits plate. This pulse is terminated upon the introduction of thetriggering signal 58 to the grid of the right tube in the multivibrator16. Since a positive pulse appears on the plate of the left tube in themultivibrator 16 only during the period between the signals 52 andplates of the left and right tubes are complementary,

signals 50 and 52 and between the signals 58 and 60.

Ihnlike manner, the negative slope of the pulse 64, co-

off. The resultant positive pulse, indicated at 70, which is produced onthe plate of the left tube in the multivibrator 18, continues until thetriggering signal 60 is introduced to the grid of the right tube in themultivibrator 18. The right tube in the multivibrator 18 then becomescut oit and the left tube again conducts. Thus, a single positive pulseappears on the plate of the right tube in the multivibrator 18 upon theintroduction of the triggering signal 50 'and continues until theintroduction of the triggering signal 58. This pulse is illustrated at72 in Figure 2.

. In addition to .being introduced to the grid of the left tube in themultivibrator 16, the voltage on the plate of the left tube in themultivibrator 14 is introduced to the grids of the two tubes in thebiased multivibrator 32. The left tube of the biased multivibrator 32normally conducts, but upon the introduction of a positive signal to thegrids of the two tubes in the multivibrator, the multivibrator becomesfree running and the two tubes alternately conduct to produceoscillatory signals having a predetermined length, such as 30microseconds. The positive signals produced in an oscillatory manner onthe plate of the left tube in the biased multivibrator 32 are indicatedat 74 in Figure 2. As previously explained, these oscillatory signalsoccur between the triggering signals 50 and 52 and between the signals58 and 60. Similarly, oscillatory signals, indicated at 76, are producedon the plate of the left tube in the biased multivibrator' 36 during theperiod between the triggering signals 52 and 58. This results from thefact that the positive pulse 64 appearing on the plate of the left tubein the multivibrator 16 during the period between the signals 52 and 58is introduced to the grids of the two tubes in the multivibrator 36.

The gating stages 40, 34 and 42 conduct when positive signals aresimultaneously introduced from at least one ol the bistablemultivibrators 14, 16 and 18 and one of the biased multivibrators 32 and36. Thus, the gating circuit 40 passes the oscillatory signals from thebiased multivibrator 32 only during the period between the triggeringsignals 50 and 52, since the positive signal on the plate of the righttube in the multivibrator 16 and the positive signal on the plate of theright tube in the multivibrator 18 coincide only during this period. Theoscillatory signals from the gating circuit 40 are illustrated at 78 inFigure 2.

Similarly, during the period between the triggering signals 52 and 58,the positive pulse 62 on the control grid of the pentode in the gatingcircuit 34 coincides with the positive oscillatory signals 76 on thesuppressor grid of the pentode. The gating circuit 34 conducts andchannelizes the oscillatory signals into a separate output through thelead 48, as illustrated at 80 in Figure 2.

The gating circuit 42 conducts during the period between the triggeringsignals 58 and 60 as a result of the positive pulse 70 from the plate ofthe left tube in the multivibrator 18, and the positive oscillatorysignals 74 from the plate of the left tube in the biased multivibrator36; The positive oscillatory signals, indicated at 82, are channelizedinto a separate output through the lead 46.

The system disclosed above has several advantages. It provides apositive indication of the time periods between successive triggeringsignals by producing positive signals at predetermined intervals duringeach period. The time indication may be made as accurate as desired byreducing the time required to produce each oscillatory signal in themultivibrators 32 and 36. The oscillatory signals can be easily countedand can be easily stored for subsequent recordation and analysis toprovide an efiicient and reliable time indication. Furthermore, thesystem passes the positive oscillatory signals between the differentpairs of adjacent pulses into separate channels to facilitate thesubsequent recordation and analysis. The system employs a minimum numberof stages to provide the time indications. For example, only the twomultivibrator stages 32 and 36 are required to produce oscillatorysignals for three channels.

Although this invention has been disclosed and illustrated withreference to particular applications, the principles involved aresusceptible of numerous other applications which will be apparent topersons skilled in the art. The invention is, therefore, to be limitedonly as indicated by the scope of the appended claims.

a particular one of the e particular output terminal of What is claimedis:

l. In combination, a pulse source for providing a plurality of pulses ina sequence, iirst, second and third bistable multivibrators each havinga pair of input terminals and a pair of output terminals, both inputterminals of the first multivibrator being connected to the pulsesource, one of the input terminals of the second and thirdmultivibrators being connected to the pulse source, the other inputterminal of the second multivic'rator being connected to a particularone of the two output terminals of the first multivibrator, the otherinput terminal ot the third multivibrator being connected to two outputterminals of the second multivibrator, a first oscillator connected tothe particular output terminal of the first multivibrator and responsiveto a particular state of equilibrium in the multivibrator to producesignals at particular intervals during the period between the first andsecond pulses from the source and during the period between the thirdand fourth pulses from the source, a second oscillator connected to theparticular output terminal of the second multivibrator and responsive toa particular state of equilibrium in the multivibrator to producesignals at particular intervals during the period between the second andthird pulses from the source, and first, second and third gating stagesconnected to a particular one of the oscillators and to a particularoutput terrninal of a particular multivibrator and responsive to aparticular state of equilibrium in the multivibrator to pass in sequencethe oscillatory pulses produced between the successive pairs of adjacentpulses in the sequence.

2. In combination, a pulse source for providing a plurality of' pulsesin a sequence, first, second and third bistable multivibrators eachhaving a pair of input terminals and a pair of output terminals, theinput terminals of the first multivibrator being connected to the pulsesource, one of the input terminals of the second and thirdmultivibrators being connected to the pulse source, the other inputterminal of the second multivibrator being connected to a particular oneof the two output terminals of the first multivibrator, the other inputterminal of the third multivibrator being connected to a particular oneof the two output terminals of the second multivibrator, a iirstoscillator connected to the the first multivibrator and responsive to aparticular state of equilibrium in the multivibrator to produce signalsat particular intervals during the period between the first and secondpulses from the source and during the period between the third andfourth pulses from the source, a second oscillator connected to theparticular output terminal of the second multivibrator and responsive toa particular state of equilibrium in the multivibrator to producesignals at predetermined intervals during the period between the f;second and third pulses from the source, a first gating stage connectedto particular output terminals in the second and third multivibratorsand to the first oscillator to pass signals during the period betweenthe first and second pulses from the source, a second gating stageconnected to the other of the two output terminals in the firstmultivibrator and to the second oscillator to pass signals during theperiod between the second and third pulses from the source, and a thirdgating stage connected to a particular output terminal in the thirdmultivibrator and to the first oscillator to pass signals during theperiod between the third and fourth pulses from the source.

3. In combination, a pulse source for providing a plurality of pulses ina sequence, a first bistable member connected to the pulse source tochange from its original state of equilibrium and to return to itsoriginal state of equilibrium upon from the source, a second bistablemember connected to the first bistable member and to thepulse source tochange from its original state of equilibrium upon the return of thefirst bistable member to its original state of equithe introduction ofalternate pulsesr libriurn and to return to its original state ofequilibrium upon the introduction of the next pulse from the source, athird bistable member connected to the second bistable member and to thepulse source to change from its original state of equilibrium upon thereturn of the second bistable member to its `original state ofequilibrium and to return to its original state of equlibrium upon theintroduction of the next pulse from the source, a pair of oscillatorymembers connected to particular bistable members to produce signals atparticular intervals during the period between each pair of successivepulses from the source, and first, second and third gating stagesconnected to particular oscillators and to particular output terminalsof' particular multivibrators and responsive to particular states ofequilibrium in the multivbrators to pass in sequence the oscillatorysignals produced between the successive pairs of adjacent pulses in thesequence.

4. In combination, a pulse source for providing a plurality of pulses ina sequence, a first bistable member connected to the pulse source tochange from its first state of equilibrium to its second state ofequilibrium and to return to its first state of equilibrium upon theintroduction of alternate pulses from the source, a second vbistablemember connected to the first bistable member `and to the pulse sourceto change from its first state of equilibrium to its second state ofequilibrium upon the return of the first bistable member to its firststate of equilibrium and to return to its first state of equilibriumupon the introduction of the next pulse from the source, a thirdbistable member connected to the second bistable member and to the pulsesource to change from its first state of equilibrium to its second stateof equilibrium upon the return of the second bistable member to itsfirst state of equilibrium and to return to its first state ofequilibrium upon the introduction of the next pulse from the source, afirst oscillatory member connected to the rst bistable member to producesignals at particular intervals during the operation of the bistablemember in its second state of equilibrium, a second oscillatory memberconnected to the second bistable member to produce signals at particularintervals during the operation of the bistable member in its secondstate of equilibrium, a first gating member connected to the second andthird bistable members and to the first oscillatory member to passoscillatory signals only during the period between the first and secondpulses from the source, a second gating member connected to the firstbistable member and to the second oscillatory member to pass oscillatorysignals only during the period between the second and third pulses fromthe source, and a third gating member connected to the third bistablemember and the first oscillatory member to pass signals only during theperiod between the third and fourth pulses from the source.

5. In combination, means for providing a plurality of pulses in asequence, a plurality of pulse forming stages connected to the pulseproviding means for producing between each successive pair of adjacentpulses in the sequence a pulse having a width proportional to the timeperiod between the pair of adjacent pulses, a plurality of timing stagesconnected to the pulse forming stages for producing signals atparticular intervals during the production of each pulse by the pulseforming stages, and gating means connected to the pulse forming stagesand the timing stages to separate the timing signals produced during theproduction of each pulse by the pulse forming stages.

6. In combination, a triggering source for providing a plurality ofpulses in a sequence, a plurality of stages connected to the triggeringsource in cascade relationship to one another for becoming actuated insuccession between successive pairs of adjacent pulses in the sequence,a plurality of timing stages connected to the first mentioned stages toproduce a number of signals at particular intervals during theactivation of each of the first' mem tioned stages, and a plurality ofgating stages connected to at least one of the first mentioned stagesand to one of the timing stages to pass in sequential pattern thesignals formed by the timing stages during the activation of the firstmentioned stages.

7. In combination, a pulse source for providing a plurality of pulses ina sequence, first, second and third triggering stages connected to thepulse source to become activated in sequence during the periods betweensuccessive pairs of adjacent pulses in the sequence, first and secondoscillatory stages connected to the triggering stages to produce signalsat particular intervals during the activation period of each triggeringstage, and rst, second and third gating stages each of the gating stagesbeing connected to particular triggering and oscillatory stages toprovide a separate output for the sequential passage of oscillatorysignals produced during the activation period of each triggering stage.

8. In combination, a pulse source for providing a plurality of pulses ina sequence, first, second and third triggering stages arranged incascade relationship and connected to the pulse source for becomingactivated in succession during the periods between successive pairs ofadjacent pulses in the sequence, first and second oscillatory stagesconnected to the first and second triggering stages respectively foractivation alternately by pulses from the rst and second triggeringstages to produce signals at substantially constant intervals during theactivation periods of the oscillatory stages, a first gating stage connected to the second and third triggering stages and to the rstoscillatory stage to pass the signals from the oscillatory stage duringthe simultaneous activation of the triggering stages, and second andthird gating stages connected to the second and first oscillatorystages, respectively, and to the first and third triggering stages,respectively, to separate the signals from the second and firstoscillatory stages during the activation of the first and thirdtriggering stages, respectively.

9. In combination, a pulse source for providing a plurality of pulses ina sequence, first, second and third triggering stages arranged incascade relationship and connected to the pulse source to becomesuccessively activated during the periods between successive pairs ofadjacent pulses in the sequence, the first triggering stage beingconnected to the pulse source for activation during the period betweenthe first and second pulses in the sequence and during the periodbetween the third and fourth pulses in the sequence, first and secondoscillatory stages connected to the first and second triggering stages,respectively, to provide signals recurring at particular intervalsduring the activation of the associated triggering stage, and first,second and third gating stages connected to particular triggering andoscillatory stages to pass sequentially through the first, second and.third gating stages the recurrent signals produced during the activationof the first, second and third triggering stages, respectively.

10. In combination, a pulse source for providing a plurality of pulsesin a sequence, a first triggering stage connected to the source foractivation during the period between the first and second pulses in thesequence and during the period between the third and fourth pulses inthe sequence, second and third triggering stages connected to the pulsesource for activation during the periods between the second and thirdpulses and between the third and fourth pulses in the sequence,respectively, a rst oscillatory stage connected to the first triggeringstage to provide signals recurring at particular intervals during theactivation periods of the first triggering stage, a second oscillatorystage connected to the second triggering stage to provide signalsrecurring at predetermined intervals during the activation period of thesecond triggering stage, and first, second and third gating stages eachconnected to at least one of the triggering stages and one of theoscillatory stages to pass sequentially through the first, second andthird gating stages the recurrent signals produced by the oscillatorystages during the activation of the rst, second and third triggeringstages, respectively.

2,272,070 Reeves Feb. 3, 1942 8 Meachem Nov. 1, 1945 Grosdot July 16,1946 Sallach June 15, 1948 Crost June 29, 1948 Cleeton July 6, 1948Atwood et al. Oct. 10, 1950 Melhose Feb. 13, 1951 Trevor Feb. 27, 1951

